Non-contact IC card technology having a nonvolatile memory and a wireless communication chip (FeliCa®; see Non-Patent Document 1) has recently developed. In the non-contact IC card technology, a non-contact IC is incorporated into various types of cards, and by holding this IC card over a reader/writer, it is possible for the IC card to transmit and receive data with the reader/writer. Further, since the non-contact IC cards use the electric power generated based on electromagnetic waves radiated from the reader/writer as their power source, they do not need to include a battery or the like therein so that the structure thereof can be simplified and that they never run out of battery to be unusable. Therefore, the IC cards are utilized, for example, as a prepaid IC card (Suica®), a credit card for electronic payments (Edy®), an employee ID card, and the like.
Recently, attempts have been made to apply the functions of the non-contact IC card to wireless telephone devices. Since the wireless telephone device stores various kinds of information, the importance of lock function as a measure for preventing the information from leaking has been increasing. Typically, wireless telephone devices have various lock functions that become available when a personal identification number (PIN) is inputted through user's key operation. The lock functions are such as: an all-lock, where the functions other than the limited ones such as power on/off or emergency originating call are not usable; a mail security setting, where mails are not to be displayed; etc.
It is possible to apply the lock function of the non-contact IC cards to the lock function of the wireless telephone devices. The lock function of the non-contact IC card can be achieved by turning off the power of an IC (Faver) that provides services offered by the non-contact IC card, for example electronic payment service such as Edy®.
As a technique to unlock the above-mentioned lock functions, the operation, for example, to input a PIN at an unlock screen of the above-described all-lock or mail security setting is required. Alternatively, as disclosed in Patent Document 1 below, the unlocking can be achieved by holding another external IC card over a reader/writer to which FeliCa IDm has been registered in advance, after a simple operation, in order to verify the FeliCa IDm which is the unique data of the external IC card. With this, it is possible to prevent improper unlocking because the unlocking is not able to be achieved if the person unlocking does not have the card with him/her. This also is a convenient function because the time for inputting the PIN can be saved if the user has the card with him/her. Further, the above-mentioned authentication for performing unlocking can be utilized as an IC card authentication function.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-54305
Non-Patent Document 1: Overview of FeliCa The FeliCa system, [online], Sony Corporation, [searched on Feb. 16, 2007], the Internet <URL: http://www.sony.co.jp/Products/felica/abt/dvs.html>